Gust or no gust?
 

Having followed this interesting thread, I still have some questions (no pilot, just engineer, airframes):

- in nearly all post, it seems to be a given, that the A/C was hit by a gust or even two. But was it really? Or could the same, let say, 'manoeuvre', also be explained for a steady crosswind and pilot 'actions'?

- was the late turn into the wind just before touch-down a 'active' pilot manoeuvre to correct an otherwise misaligned approach back to the centreline? Or was it an manoueuvre to compensate a gust? The latter possibility seems unlikely to me, as no additional drifting of the A/C can be observed prior to the manoueuvre and there would always be a time lag between a gust and the reaction to it....

- given, that it was a late corrective effort to get back to center line (regardless if due to gust or not enough crab angle before), would the need for such a 'significant' corrective action shortly before touch-down commonly be regarded as a trigger for a 'go-around' or would you try to proceed anyway?

- To me the A/C seems already slighty banking to the downwind side during de-crab. Wouldn't a strong de-crab manoeuvre by rudder-input not necessarily result in a roll-moment to the down-wind-side due to yaw-roll coupling (again no pilot, just rough flight mechanics knowledge....)? And, secondly, could it be that this roll-moment just has not been compensated sufficiently and thus letting the A/C bank, exposing the upwind wing, and so on .....So there would be no necessity for a gust during de-crab to explain the drift downwind?


Just my thoughts following your discussion. I guess only the pilots themselves will exactly know the chain of events. But, bottom line, for me it would interesting, if the same incident can be explained without the alleged gust, but also with a nearly steady crosswind component and too late and maybe too strong corrective actions of the crew?

Regards, ihg

sevenstrokerol, Frosch and callimoucho are seemingly asking these questions:I'm just wondering, why are you asking ?

The incident report will have all the relevant data. I myself don't care what the pilots names are. I am absolutely sure the authorities and Lufthansa will take any relevant and needed training / personnell / discipline actions, should there be any, which I doubt.

I do not understand why anyone NEEDS to know NOW who was flying the aircraft for this approach. That will come out in the enquiry report.

From my own experience and comments on this thread, we do not need to consider the Airbus form of flight controls.

What little information we have is shown on the recorded videos portrayed on YouTube and others.

From those video clips we might deduce whether the control inputs were effective. Or whether an alternative crosswind landing technique might have been more useful.

Discussion on these 2 aspects would be appreciated!

I do however commend the crew decision to abort that particular approach in favour of another when the wind would be more favourable!

Captain's landing in marginal weather? Well, my present and past airlines practise that. However, there were cases where the humble eff oh did a better job.
Years ago in another life flying the old A300 B4 into old Kai Tak at the onset of a typhoon. X-Winds were within limits but very gusty. After the checker board, we were turning beautifully for a textbook gusty X-W landing when a mighty gust turned everything pear shaped! The wings went wiggy waggy, the concentration and focus throughout the whole IGS 13 approach was so intense that the skipper ended up with tunnel vision and keep struggling to salvage the landing. The F/E was pretty quiet; the young F/O just grunted " GO A... " and pressed the Go levers! In a daze the skipper and F/O struggled together for a split second before, unbelievably, the skipper shouted " you have control " and the young f/o took it around. The skipper , ashen faced, with shaking knees and squeaky voiced asked the f/o to fly to TPE. Since we had plenty of fuel ( no problem with 8 extra tons ), the young f/o proposed another try. Skipper agreed with f/o flying..well f/o brought it down beautifully on the IGS to an equally beautiful landing. Later we celebrated at the bicycle bar!
The skipper was : YOURS truly. The F/O... well he has moved on to become a great skipper. The F/E; he probably learnt a lot that day and too took up flying as f/o and is now a junior skipper!

Great Story OKhalsa;)

Its's with those lil pieces of Humble Airmanship that all of us in this crazy Aviation World could have somethin'to learn and enjoy...:)

Cheers, My Friend:ok:

to some degree, yes.

they have.

Thanks JanetFlight. It was a humbling experience and it showed what tunnel vision can do. The F/O swore that he called Go Around 2 times ( the F/E meekly confirmed that ) before hitting the go levers on the third call! I swear I only heard him mumbled the last one!! My only lame excuse was it was the third leg after an early morning start.

gargelblaster and others:

why did I want to know who was pilot flying? because the landing , (regardless of the fly by wire vs non fly by wire control methods), was just that bad. the lack of "keeping the right wing down, or at worst, level, really seemed like something an inexperienced pilot would allow to happen.


the "der spiegel" article seems to confirm that the copilot was pilot flying.

the copilot was 24 years old. the captain 39. even assuming that they both learned to fly at age 17, the 24 year old had 7 years of experience and the captain had 22 years experience.

experience does matter. method of training matters. the only real question now is why did the captain let the copilot do the landing if it was such a bad day?

was the captain a training captain/check airman etc.?

and just in case you think my concern is gender related, it is not. it is experience related.

does this answer your question?

Its not experience that matters, it’s what you do with it.
 

Its not experience that matters, it’s what you do with it.
The First Officer might actually be an excellent stick and rudder person, or even more ‘experienced’ in those particular conditions; we don’t know.
Similarly there are many unknown aspects; what was the ‘actual’ wind, or at least the tower report on which (presumable) a decision to land would be taken?
Was the runway wet? If so this should have influenced the decision to land – crosswind landings aren’t just about getting onto the runway, you have also got to stay on the runway, and just because the subsequent landing was ‘OK’ doesn’t mean that it was safe or justified.

JanetFlight, could not agree more...nice call.

OKhalsa;

A fine aviator's story, thanks.
Re, An F/O friend suggested a solution to tunnel vision; I've seen it used, ...once, and it did save the day. FWIW:

The first word/sound we recognize in almost all situations including high-stress ones is our name.

Tunnel-vision can be tough to break through but using the PF's name can help do that...If "Jack" is the PF and it's going to be a mess, how about:

"JACK!, JACK! - GO-AROUND, GO-AROUND, JACK!!) instead of just calling Go-around? A thought...

PJ2

Theory and Practice
 

Quote from exeng Mar02/00:18:
As a former Boeing man the first on limits Xwind landing on a 320 at LHR scared me. The training I had on the sim was just that - training on the sim. I had full sidestick and the wing just kept on coming up. In the end I released some rudder (in panic. I might add, whilst trying to just fly the plane) and landed with a considerable amount of drift on.
Because of this experience I made some considerable noise in the office [....] and was given the advice that I 'probably just wasn't applying the correct techniques'. In other words - just go away.
Fortunately I mentioned this experience of mine to a 320 'old hand' who advised that the rubbish taught in the sim is just that - the drift has to be taken off earlier in the 320 so as to give the 'bus' some small time to rethink.
[Unquote]

Trouble is (unless things have changed since my day), the hard-pressed pilot-managers are just too busy flying their desks and issuing memos to get out and remind themselves what the whole thing is really about. And even the trainers don't get enough "polling" themselves (as opposed to watching their students doing it).

It is not necessary or desirable to use the full sideslip technique in a strong crosswind, which is the implication of what you are saying. The sideslip angle required would put you too close to the possibility of pod-scrape/flap-scrape/winglet-scrape (depending on the pitch attitude).

The most reliable technique in my experience is to induce slight sideslip during de-crab, i.e., to pre-empt the tendency of the upwind wing to rise because of the de-crab yaw**, AND to pre-empt a possible gust. 5 degrees of bank is about right. Limit the amount of flare. DO NOT TRY TO "GREASE" HER ON. Then, allow the downwind wheels to touch down immediately after the upwind ones. At this point, FBW ground Law will commence, and a suitable increase in into-wind aileron can be applied. This can be maintained until about 80 kts, to be on the safe side.
In my day, Medium autobrake was recommended in a strong crosswind, but it complicates the situation if you need to use differential brake to correct a swing. Runway length and state permitting, manual brake and idle reverse are the best option for directional control. If memory serves, rudder-fine (nosewheel) steering is not available above 72 kts GS. You may need differential brake to hold straight as the rudder itself gradually loses authority.

** [The FBW should counteract this. In practice, I often observed it fail to do so. Trainers have to teach the "book".]

Quote from lambourne [Mar02/00:59]:
I did not find the AB roll rate algorithm intuitive to adapt to. On this flight, I announced "full left sidestick" to my F/O and we touched down in a manner resembling tossing a pillow case full of doorknobs onto the runway. After we exited he said that hitting the stops was common occurrence on the bus in strong crosswinds. I said I had just spent 6 weeks in training and at no point did anyone in the schoolhouse find it somewhat needful to convey that you might hit the stops.
The bus is a bit like tail wheel airplane. Great on a calm or wind down the runway day, but a handful in strong x-winds
[Unquote]

Full roll-demand is not normally necessary if you use the technique I describe above. But gust-induced rise of the upwind wing must be dealt with promptly, i.e., try to keep the wing slightly down until the upwind wheels are firmly on.

Having flown the tailwheel-Dakota (only 450 hrs, admittedly), as well as numerous large jets before the A320, I cannot agree with the last sentence... The A320 behaves like most tricycle-gear jet airliners. Once the nosewheel is on the runway with ground spoilers (lift dumpers) extended, the necessity for differential brake is unusual. On the Dakota, as you allowed the tail to settle at about 50kts, your problems were often just beginning...

I find it alarming that many of the Bus pilots posting here are under the impression that flight control laws change to direct at 50ft.

It makes me wonder if more and more carriers are using AQP and are providing pilots with heavily redacted training manuals.

Ihg,

As I stated in a previous post, the last 100 feet of a crosswind landing can be very challenging. During a crosswind landing, the airport layout can come into play. If there are tall buildings, terminals, hangars, or even tall trees adjacent to the runway, the air can become quite unstable. If you've ever driven across a suspension bridge during high sidewinds, notice how unstable your car becomes when it passes the main support beams that block the airflow. In the video the aircraft appears to be fairly stable and tracking the centerline until just about 100 feet. The drift appears to accelerate, there's a correction back to centerline and then during the flare everything starts to go south. Unfortunately, at that point things are happening fast and you only have a few seconds to make a decision. Fortunately, for all involved, everybody walked away.

seventhree;

Not only do checked-out Airbus pilots believe that the laws change around 50ft, but they also believe that the Airbus will "lower the wing" into wind when decrabbing, to keep the track straight - it's a very widely-held belief.

If they believe that, why don't they just fly the thing in with one wing low?

Stick and rudder skills being valued in 2008?

Marty1468;
Because they believe the airplane will do it when required :bored: ...

Regardless, there are a number of misconceptions regarding the airplane as witnessed by the 2000+ posts on the TAM accident, many of which did not indicate understanding of the airplane, (while some, I hasten to add, revealed an astonishing depth of understanding which benefitted us all - thinking of ELAC here among others). I can see why though...the airplane itself takes a good six months to a year to get accustomed to and perhaps the same amount of time to get to the stage of "strapping it on" and even then, one may not be aware of all the C* law nuances.

@ seventhree:

Pitch goes gradually to direct, roll not. And that makes it tricky...
Rudder is always direct.
Pitch direct is blended in gradually and reached around 50ft and even a light nose down momentum is induced to you make you pull the stick. Stabilizer position is also a key factor for pitch control (if it's bad you can hit the mechanical stop of the stick).

@ PJ2:

I'm an Airbus Pilot and I know that the wing will not be lowered automatically. You can decrab an A320 almost like a conventional aircraft, it feels just a little bit different. It's a little bit shaky because you always have to counteract the roll normal law.

CM - I disagree :ugh: As has been stated numerous times here, Pitch and Roll remain Normal Law until 5s after touchdown...

All that happens @ 50' on Approach is that the "datum" attitude tries to reduce to require a "flare input". Law remains Normal... AFAIK ;)

"Ground Mode" i.e. Direct Law is 5s after landing

NoD